[vtkusers] BooleanOperationPolyDataFilter Problems

[Cory Quammen]

>
> A few years ago I wrote a filter called vtkContourTriangulator that can
> sometimes be used as a stable replacement for vtkDelaunay2D.  However,
> vtkContourTriangulator is not as fast as vtkDelaunay2D, nor does it produce
> high-quality triangles (i.e. it does triangulation, but not Delaunay
> triangulation).
>

It's worth mentioning that I quickly tried swapping vtkContourTriangulator
in place of vtkDelaunay2D a while back, but didn't quite get it to work. I
didn't spend a lot of time on it, though, so it may be worth investigating
again if someone wants to try. The quality of the triangles isn't that
important for the boolean operations IMHO, and you can get some high-aspect
ratio triangles with the constrained Delaunay triangulation that the
boolean operation filters currently use.

- Cory


>  - David
>
> On Wed, Jul 5, 2017 at 5:42 AM, updega2 <updega2 at berkeley.edu> wrote:
>
>> Hi, I authored the LoopBoolean a few years ago because we wanted a more
>> reliable vtk-based boolean to use in our software.
>>
>> I've mentioned this before I believe on the merge requests, but I think it
>> may be helpful to say it again here. When the booleans fail (current and
>> the
>> LoopBoolean), it is typically during re-triangulation due to
>> vtkDelaunay2D.
>> I developed the LoopBoolean using vtk 6.0. After vtk 6.0, some changes
>> were
>> made to the vtkDelaunay2D code, which caused many more issues in the
>> LoopBoolean. I tried working with the vtkDelaunay2D author to fix some of
>> the Delaunay bugs, and we got a couple fixed, but a few remain.
>>
>> So, in our software, we actually have a copy of the vtkDelaunay2D code
>> from
>> the vtk 6.0 pipeline, and the LoopBoolean calls that. The code works well
>> for our purposes. It still isn't bug free as the code is tolerance-based,
>> and there are orientation tests that may fail from time to time due to
>> tolerance issues. Also, I'll admit that error checking could be better. I
>> would like to go back and improve this part of the code, but haven't had
>> the
>> time yet.
>>
>> Adam
>>
>>
>>
>> --
>> View this message in context: http://vtk.1045678.n5.nabble.c
>> om/BooleanOperationPolyDataFilter-Problems-tp5743863p5743900.html
>> Sent from the VTK - Users mailing list archive at Nabble.com.
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>
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-- 
Cory Quammen
Staff R&D Engineer
Kitware, Inc.
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